Bile acid in intestine (BAs)

Bile acids are amphipathic steroid-derived metabolites synthesized in the liver from cholesterol and released into the intestine after meals, where they aid in the emulsification and absorption of dietary fats. In the intestine, primary bile acids are modified by the microbiota to secondary bile acids. Beyond their digestive role, bile acids serve as versatile signaling molecules by binding to specific cell-surface and nuclear receptors, notably FXR and GPBAR1, thereby regulating energy metabolism, intestinal motility, immune response, and maintaining gut-liver homeostasis. Clinically, alterations in bile acid composition or their signaling have major roles in conditions such as cholestatic liver diseases, IBD, colorectal cancer, and metabolic syndrome. Bile acid-modifying drugs target these signaling axes for therapeutic benefit, but abnormal bile acid levels can be toxic and are associated with both local and systemic disease processes.

Other names

Bile acidsintestinal bile acidsBAs

Activation or inhibition of bile acid receptors (e.g., FXR and GPBAR1), thereby modulating metabolic, inflammatory, and proliferative signaling pathways; also, dissolution or modulation of the bile acid pool (as with bile acid therapies for gallstones).